LeetCode(43)-Contains Duplicate II

题目：

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between i and j is at most k.

思路：

• 给定一个数组a，和一个整数k，题意是判断一个数组里面，有没有重复的两个元素，坐标是i和j，且i和j只差大于等于k。
• 考虑用hashMap

代码：

public class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        if(nums==null || nums.length<2) return false;
        //key=int, val=index
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for(int i=0; i<nums.length; i++) {
            if(map.containsKey(nums[i])) {
                int j = map.get(nums[i]);
                if(i-j<=k) {return true;

                }else{
                    map.remove(j);
                    map.put(nums[i], i);
                }
            } else {
                map.put(nums[i], i);
            }
        }
        return false;
    }
}